I have read in a few places that Mimosa Pudica does not contain DMT, however it contains other alkaloids but not any of interest, such as this one: http://en.wikipedia.org/wiki/Mimosine (might be of interest to biologists, it arrests cell division or something)

There are lots of other plants though that contain DMT, but the extraction process is a pain and it takes more work than it is generally worth for a lower quality extract. Phalaris Arundinacea, for example. There is lots of literature on it, and I get the feeling you'll already know about it.

Other hostilis plants likely contain DMT, though probably not as much - I believe they are slightly related to the Acacia species. If you are lucky and live in a good place you'll likely find lots of active Acacia species... Not to sure if they are worth the time and effort, however.

This link will likely be of interest if you have not already found it: http://en.wikipedia.org/wiki/List_of_psychedelic_plants